This invention relates to the preparation of plastic containers, especially composite parisons having a preformed inner sleeve or lining, said parisons being useful in the formation of composite blow molded containers as described in my prior U.S. Pat. Nos. 3,719,735 and 3,717,544. According to said patents, previously formed sleeve-like liners are applied to a blow core of an injection blow molding apparatus, plastic is injected around said liners while upon the cores and the resultant composite parison, consisting of the liner and the injected plastic, is expanded together into conformance with a blow mold. The method of injection blow molding is well known and described, for example, in U.S. Pat. No. 3,029,468 and others.
It is highly desirable to adjust the temperature of the blow core so as to condition the blow core to render it suitable for receiving and heating the preformed sleeve prior to injection of plastic therearound. One may provide the core with internal heating coils, or heat exchange fluid channels, or make the core of a good heat conductor to minimize temperature gradients therein; however, it is often found that these expedients render the core and core assembly mechanically cumbersome and subject to damage.
Accordingly, it is a principal object of the present invention to provide a process and apparatus for making plastic containers, especially composite containers having an inner lining applied to a core prior to the formation of the composite.
It is a further and particular object of the present invention to provide a process and apparatus as aforesaid which enables adjustment of the core temperature and conditioning of the core prior to application of the liner thereon in a simple, convenient and expeditious manner suitable for commercial operation.
Further objects and advantages of the present invention will appear from the ensuing specification.